Elastic study and optical dispersion characterization of Fe-substituted cobalt aluminate nanoparticles

The point of this work is to study the impact of Fe3+ ions substitution on the structural, elastic and optical properties of CoAl2O4 nanoparticles. A series of CoAl2−xFexO4 nanoparticles, 0.00 ≤ x ≤ 0.20, are prepared by chemical co-precipitation method. X-ray diffraction besides the FTIR examination affirms the forming of single-phase cubic spinel CoAl2O4 for Fe3+-substituted samples. The lattice constant a is found to be increased with increasing Fe3+ content obeying Vegard’s law. The dependence of theoretical density, porosity and crystallite size on Fe3+ content x is discussed. FTIR spectral analysis is used to estimate the elastic moduli such as stiffness constant, Young’s modulus, rigidity modulus, bulk modulus, Poisson’s ratio, wave velocity and Debye temperature. The stiffness constants and Poisson’s ratio increase with the increase in Fe3+ content due to the decrease in porosity and substitution process. The values of Young’s modulus, rigidity modulus and Debye temperature reduce with an increase in the Fe3+ content, whereas the bulk modulus increases with x. The optical properties of CoAl2–xFexO4 nanoparticles are analyzed using UV–Vis spectrophotometer measurements in the spectral range of 200–1100 nm. Some of dispersion parameters are evaluated based on a single oscillator model, such as oscillator energy Eo, dispersion energy Ed, lattice dielectric constant el, the average value of oscillator strength, SO, and wavelength of single oscillator λO. The most important result of the current work is the use of Fe3+ ion substitution in CoAl2O4 nanoparticles, which can be used to modify the elastic moduli, optical band gaps and dielectric constant.